1. Field of the Invention
The present invention relates to an inspection apparatus.
2. Description of Related Art
Display panels, which have gone through a manufacturing process, usually undergo a lighting inspection for determining whether there are any defects such as pixel defects in the display panels. In this lighting inspection, it is necessary to supply a drive signal to a liquid crystal panel, which is the object to be inspected. Further, a circuit inspection can be performed by performing an array inspection. For example, a drive signal is supplied to a mother glass substrate before it is cut into a plurality of sections. Therefore, the inspection apparatus is provided with, as its inspection station, an electric inspection apparatus including an inspection pedestal on which a liquid crystal panel, which is the object to be inspected, is placed in a state where its electrodes face upward, and a probe unit supported on a fixed frame body disposed above the object to be inspected.
As this type of an electric inspection apparatus, Japanese Unexamined Patent Application Publication No. 2010-112919 discloses an inspection apparatus for a liquid crystal panel. In this inspection apparatus, a rectangular liquid crystal panel, which is an object to be inspected, is placed on an inspection pedestal. A rectangular fixed frame body having sides corresponding to the respective sides of the rectangular liquid crystal panel is disposed above the inspection pedestal. Further, a number of probe assemblies are arranged along a pair of sides adjoining at right angles of the fixed frame body. More specifically, probe stage plates are supported on edges of the fixed frame body. Probe units are attached to the probe stage plates.
Each probe unit includes a support base member and a plurality of probe assemblies. The support base member is fixed to the probe stage plate in a removable fashion. The probe assemblies are supported on the probe stage plates. Each probe assembly is supported on the support base member through its suspension mechanism so that its probes are opposed to corresponding electrodes of a liquid crystal panel. For each suspension mechanism, a signal circuit substrate is supported below that suspension mechanism. A drive signal is supplied to a predetermined probe of the probe assembly through a liquid crystal drive IC circuit composed of an IC chip provided in each signal circuit substrate.
Therefore, in the electric inspection apparatus, the relative position of a liquid crystal panel placed on the inspection pedestal is adjusted so that each electrode provided in that liquid crystal panel is aligned with a respective one of the probes of the probe units supported on the fixed frame body. After this position adjustment, when the tips of the probes of each probe assembly provided in each probe unit come into contact with corresponding electrodes of the liquid crystal panel by the movement of the inspection pedestal toward the fixed frame body, drive signals are sent from predetermined probes to the corresponding electrodes through the IC chip. The liquid crystal panel is brought into a lighting state and maintained in the lighting state for a certain time period by these drive signals, and the liquid crystal panel undergoes a predetermined inspection(s).
In the above-described inspection apparatus, the suspension mechanism is electrically connected to the housing of the prober. Further, the housing is electrically connected to the ground (GND). A current leak could occur due to a capacitive coupling of a probe stylus and a signal circuit substrate. That is, as the housing is connected to the GND, when the GND level fluctuates due to noises caused by the prober or the factory, part of the current of the tester circuit could leak through the capacitive coupling. Therefore, there is a possibility that measurement variations may occur due to these noises.
The present invention has been made in view of the above-described problem, and an object thereof is to provide an inspection apparatus capable of reducing the effect of noises.